A single step non-catalytic esterification of palm fatty acid distillate (PFAD) for biodiesel production

In this work, the single step method for non-catalytic esterification of palm fatty acid distillate (PFAD), which is readily applicable to actual production of biodiesel, was investigated. In this method, the esterification reaction is accomplished in a single step by ensuring water-free reaction conditions and the acid value is reduced to below 0.5 (mg KOH/g) which has not been possible in previous methods. The reaction was completed (<0.5 mg KOH/g) within 180 min at relatively high temperature (>250 °C) enough to be above boiling point of water and at moderate pressure (0.85–1.20 MPa) without any catalyst. The effects of temperature, methanol feed rate and pressure on a semi-batch reaction were investigated and the optimal values of these variables were found (temperature: 290 °C, pressure: 0.85 MPa, feed rate: 2.4 g/min). The acid value was reduced from 191.4 to 0.36 (mg KOH/g) just in 180 min at these conditions. From the kinetic study on non-catalytic esterification of PFAD, it was found that the activation energy is 17.74 kJ/mol and the frequency factor is 2.12 min−1.